It is of great importance that our animals get satisfying sedation before procedures and surgery. In animal welfare perspective sedation, analgesia, and effects on the cardiovascular system are important to take in consideration. There are number of different pre-anesthetic drugs used in Sweden today. The most common ones are acepromazine and alpha2-agonists. These drugs have both positive and negative effects, which is important to be aware of. Acepromazine and alpha2-agonists are often combined with an opioid to produce sufficient levels of sedation and analgesia.

The purpose of this study is to compare physiological effects of acepromazine and alfa2-agonists as pre-anesthetic medication. Alpha2-agonists are a group of medical products which primary positive effects are reliable sedation, analgesia and muscle relaxation. Alpha2-receptors are located both in the central nervous system (CNS) and in the peripheral vascular system. In CNS alpha2-agonists produce sedation and a decrease in sympathetic activity and inthe peripheral vascular system they generate a vasoconstriction. Beside the wanted effects they create side effects as bradycardia and AV-blockade which leads to a decrease in cardiac output.

Acepromazine is a phenothiazine-derived drug, which creates mild sedation with long duration in animals. The drug has an antagonistic effect on several receptors, such as h1-, serotonin-, dopamine- and alpha1-receptor. The sedative effect is produced threw the antagonist effect on the dopamine receptor in the CNS. The activation on the alfa1-receptor generates vasoconstriction in the peripheral vascular system and an increase in heartrate.

The intention of the present work is to investigate the effects of acepromazine and alpha2-agonists combined with an opioid on sedation, analgesia, and effect on the vascular system. When the drugs are used for premedication before surgery they are often used combined with an opioid. This produce a synergic effect with improved sedation analgesia and milder impact on the cardiovascular system than when acepromazine and alpha2–agonists work alone.

Both acepromazine and alpha2-agonists and their combination with an opioid produce good effects when it comes to sedation, analgesia and effects on the cardiovascular system. Alpha2-agonists produce a slightly more powerful sedation when it is combined with an opioid thenacepromazine combined with an opioid. The longer duration with acepromazine have some advantages compared to alpha2-agonists. The analgesic effect produced by the alpha2-agonists alone gives an advantage if the animal is going to be examined without an opioid. The different effect on the cardiovascular system by the two drugs are important to be aware of even if it only has minor clinical effects.